Historically, electrical connectors have been shielded to prevent emissions for signal wires and noise from external sources. Shielding has not been incorporated into fiber optic modules because the higher operating frequencies were believed to be immune from these effects. In reality, the fiber optic modules emit electromagnetic signals. In 47 CFR .sctn.15, the United States government has defined radiation emission regulations for commercial and consumer digital applications. For commercial applications, Class A, the radiation emission standards at frequencies above 1 Gbit/sec, at a distance of 3 m, the electrical field strength correlates to 46 dB/m. For consumer applications, Class B, the radiation emission standards at frequencies above 1 Gbit/sec, at a distance of 3 m, the electrical field strength is &lt;500 .mu.Volts/m or 54 dB .mu.Volts/m. For many products, shielding is required to meet the FCC specifications.
When fiber optic connectors are inserted through panel openings of a chassis, the "window" that allows access to a module is larger than the module. Unwanted electrical transmissions can leak through the panel opening. As a result, fiber optic products often require customized shielding for each fiber optic component. Due to manufacturing tolerance, it is difficult to have the internal and external shields interface properly.
A uniform shielding for high-speed digital applications that is easy to manufacture and reliably eliminates unwanted electrical transmissions is desirable.